1. Field of the Invention
The present invention relates to an imaging device for imaging an object.
2. Description of the Related Art
Electronic-camera imaging devices are currently on the market which record and playback static images and moving images picked up by a solid-state image pickup device including a charge-coupled device (CCD) and a complementary metal-oxide-semiconductor (CMOS) device using a memory card having a solid-state memory device as a recording medium.
The electronic cameras can be switched between a single shooting mode in which an exposure is made each time a shutter button is pushed and a continuous shooting mode in which continuous exposures are made while a shutter button is pressed by shooting-mode selection.
Also a dark-noise corrective processing is allowed in shooting with a solid-state image pickup device including a CCD and a CMOS by operating with dark image data that is read out after charge accumulation, as in main shooting, with the image-pickup device not exposed and main-shooting image data that is read out after charge storage with the image-pickup device exposed.
Therefore, the photographed image data can be corrected for picture degradation such as a dark current noise generated by the image pickup device and a pixel defect due to a minute defect inherent to the image pickup device, thus providing a high-definition image.
Particularly, since the dark current noise increases with charge storage time and an increase in the temperature of the image pickup device, the dark noise correction is useful for the user of an electronic camera because it offers a great picture improving effect in long-time exposure and high-temperature exposure.
In the related-art electronic-camera image pickup devices, as FIG. 12 shows, the following operations are performed to acquire a plurality of image data: after image data is acquired by 20-second exposure, 20-second dark data is acquired; thereafter, after image data is acquired by 20 second exposure, 20-second dark data is acquired; and after image data is acquired by 10-second exposure, 10-second dark data is acquired.
Therefore, the above continuous shooting has a problem in that the next image data cannot be acquired until after one frame of image data has been acquired, dark data is then acquired, thus increasing shutter-release time lag, so that a great photo opportunity is lost.